ABSTRACT Intensive care medicine represents an area of high intensity, high expenditure treatment with potential for large health benefits and also iatrogenic complications and unnecessary costs. Defining how to care best for an aging population when we have the capability of delivering increasingly complex interventions is a pressing concern. The elderly now represent over half of all intensive care unit (ICU) admissions in the United States, and present unique challenges for care both inside and outside the ICU. Most studies of intensive care medicine examine only those patients who are admitted to the ICU; studies that also include all hospitalized patients as a denominator are rare, yet essential to understanding how intensive care can and should be used. We recently demonstrated that the use of intensive care during terminal hospitalizations decreases with age, and varies substantially depending on the diagnosis or surgical procedure. However, studies of admission practices to ICUs and associated outcomes are confounded by variation in casemix and available resources. We plan to examine the use of intensive care by focusing on elderly patients undergoing specific high-risk surgical procedures - a more homogenous group of patients who are more likely to have a planned ICU admission compared with medical patients. We seek to test the hypotheses that ICU admission practices for elderly patients after high-risk surgical procedures vary significantly by hospital and patient characteristics, and that these variations in practice can be exploited to determine whether there are any measurable health benefits in terms of reduced complications and mortality from more aggressive use of intensive care services. We will test these hypotheses with three aims: (1) identify predictors of ICU admission practices for elderly surgical patients, (2) establish whether ICU admission practices are associated with surgical complication rates and mortality (including both hospital and one-year mortality) and (3) determine the economic consequences of different admission rates to intensive care. We will accomplish these aims through analysis of five years of inpatient Medicare data, as well as an ICU-specific dataset, Project IMPACT, that allows for a more detailed examination of the care patterns of patients prior to ICU admission. This study represents a unique opportunity both to identify ways to optimize peri-operative care, and also to address broader questions related to ICU admission practices and the risks and benefits associated with intensive care. As the availability of intensive care continues to grow, the answers to these questions are of vital importance to improve the delivery of high quality care. This award would allow me to complete the proposed study and also obtain the necessary research skills, experience, and collaborative relationships to develop into a successful and independent clinician-scientist in the area of health services research.